1. Field of the Invention
The invention relates to a frequency synthesizing circuit comprising an oscillator whose frequency is controllable by a control signal, a tuning data signal source, a digital difference-determining circuit for determining the digital value of the difference between the frequency specified by the tuning data signal source and the oscillator frequency, and a digital-to-analog converter for converting such digital difference into a control signal.
2. Description of the Related Art
In such a circuit, an input of the difference-determining circuit is coupled to the output of a gate circuit, an input of the gate circuit being coupled to the output of the oscillator and a measuring pulse input of the gate circuit being supplied with a measuring pulse by a pulse generator coupled thereto. In prior frequency synthesizing circuits of this kind the tuning frequency of the oscillator deviates on average to some extent from the frequency specified by the tuning data signal source.